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Girls call me Makaluod
1. INTRODUCTION
Balsa strops are used with cutting compounds in the final progressions of blade edge preparation. They are normally hand-held and the blade is stropped on the pasted balsawood similar to stropping on a leather strop (the progression finale).
2. OVERALL SIZE – (Don’t believe her, size does matter)
2.1 WIDTH
The balsa strop arrangement needs to (preferably) be wide enough to accommodate the length of your blade edge plus a little. If it is not wide enough, you can use the extended “X” method of stropping. Most blade edges are about 70mm (2 ¾”) long so a width of about 75mm (3”) can be ideal. If you normally use longer blades, a wider strop arrangement may be preferred. Remember though that the strop is to be hand-help so anything over about 85mm (3 ½”) may be difficult to hold.
2.2 LENGTH
The balsa strop needs to be long enough to comfortably strop upon while hand-held. If it is too long, it will be difficult to establish a good stropping technique. If too short, you will need to perform more stropping laps to achieve the same result. Balsa generally comes in lengths of about 900mm (36”) so most people appear to be happy with a balsa strop length of about 300mm (12”). Under 250mm (10”) length is getting too short and over about 450mm (15”) is getting too long.
3. THE PARTS
3.1 GENERAL
There are two main parts to the balsa strop; the balsawood and the substrate.
Balsawood
The balsawood needs to be clear and straight grained with a smooth and relatively flat surface on each side. A minimum thickness of 5mm (3/16”) is required however most prefer to work with anything from 6mm (¼”) to 12mm (½”) thickness. The thicker the balsawood the longer it will last you with multiple lapping to reset it flat. The thicker it is the more times it will need to be lapped flat due to the thickness expanding and contracting with humidity.
Substrate
The substrate needs to perform four functions:
Acrylic Sheet: There are two main types available, extruded and cast. Cast is better to use if available as it tends to not crack as easily from edge imperfections.
Relative Density = 1.18
Aluminium Alloy: Here you can use either rolled plate or extruded bar. If rolled plate, grade 5083 H321 is recommended. If extruded bar, grade 6061 T6 is recommended. Both of these grades offer good corrosion resistance and high stiffness. Other grades may also be suitable.
Relative Density = 2.7
Composite: This can be the cheapest substrate.The top can be a smooth glazed tile (about 6mm or ¼” thick) cut to size using an angel grinder with diamond disc. Onto the underside of the tile you glue (epoxy glue recommended) marine plywood (cheapest) or a closed cell structural foam (lightest) to your desired thickness.
Relative Density = 0.85 to 1.4
4. PUTTING IT ALL TOGETHER
If using a composite substrate, wait at leat 24 hours for the glue to fully set. Use a rubber glue to bond your balsawood to the substrate. Rubber glue is preferred as it allows you to later remove and replace the balsawood without damaging the top surface of your substrate. Other types of glues may be used if you so desire.
Apply some weight(s) to hold the join between the balsa and substrate in close contact. For rubber glue allow at least 24 hours for the glue to set.
Once the glue is fully set, use a flat smooth lapping plate and a sheet of sandpaper (about 320 grit) to lap the top surface of your balsawood perfectly flat. This is best done using the cross-hatch pencil method.
With the top surface of your balsawood now perfectly flat, you need to remove any loose pieces of balsawood (dust). This can be done using compressed air or a vacuum cleaner suction with a brush nozzle.
Your balsa strop is now ready for pasting.
5. EXAMPLES
Composite
300mm (12”) x 75mm (3”). 2 x 8mm structural foam + 1 x 6mm glazed tile + 10mm balsawood
Balsa strops are used with cutting compounds in the final progressions of blade edge preparation. They are normally hand-held and the blade is stropped on the pasted balsawood similar to stropping on a leather strop (the progression finale).
2. OVERALL SIZE – (Don’t believe her, size does matter)
2.1 WIDTH
The balsa strop arrangement needs to (preferably) be wide enough to accommodate the length of your blade edge plus a little. If it is not wide enough, you can use the extended “X” method of stropping. Most blade edges are about 70mm (2 ¾”) long so a width of about 75mm (3”) can be ideal. If you normally use longer blades, a wider strop arrangement may be preferred. Remember though that the strop is to be hand-help so anything over about 85mm (3 ½”) may be difficult to hold.
2.2 LENGTH
The balsa strop needs to be long enough to comfortably strop upon while hand-held. If it is too long, it will be difficult to establish a good stropping technique. If too short, you will need to perform more stropping laps to achieve the same result. Balsa generally comes in lengths of about 900mm (36”) so most people appear to be happy with a balsa strop length of about 300mm (12”). Under 250mm (10”) length is getting too short and over about 450mm (15”) is getting too long.
3. THE PARTS
3.1 GENERAL
There are two main parts to the balsa strop; the balsawood and the substrate.
Balsawood
The balsawood needs to be clear and straight grained with a smooth and relatively flat surface on each side. A minimum thickness of 5mm (3/16”) is required however most prefer to work with anything from 6mm (¼”) to 12mm (½”) thickness. The thicker the balsawood the longer it will last you with multiple lapping to reset it flat. The thicker it is the more times it will need to be lapped flat due to the thickness expanding and contracting with humidity.
Substrate
The substrate needs to perform four functions:
- Be of a size to provide support for the full length and width of the balsawood.
- Provide a flat sold non-flexible base for the balsawood so as to minimise the balsawood warping and bending.
- Be of sufficient thickness to prevent damaging your delicate manicure from the blade while stropping in hand. The preferred thickness will vary from person to person. A thickness of about 20mm (¾”) plus balsawood thickness seems to suit most people however some are happy with only 15mm (⅝”) while others prefer up to 25mm (1”).
- To have relatively low mass (weight) so as to not fategue the user during use.
Acrylic Sheet: There are two main types available, extruded and cast. Cast is better to use if available as it tends to not crack as easily from edge imperfections.
Relative Density = 1.18
Aluminium Alloy: Here you can use either rolled plate or extruded bar. If rolled plate, grade 5083 H321 is recommended. If extruded bar, grade 6061 T6 is recommended. Both of these grades offer good corrosion resistance and high stiffness. Other grades may also be suitable.
Relative Density = 2.7
Composite: This can be the cheapest substrate.The top can be a smooth glazed tile (about 6mm or ¼” thick) cut to size using an angel grinder with diamond disc. Onto the underside of the tile you glue (epoxy glue recommended) marine plywood (cheapest) or a closed cell structural foam (lightest) to your desired thickness.
Relative Density = 0.85 to 1.4
4. PUTTING IT ALL TOGETHER
If using a composite substrate, wait at leat 24 hours for the glue to fully set. Use a rubber glue to bond your balsawood to the substrate. Rubber glue is preferred as it allows you to later remove and replace the balsawood without damaging the top surface of your substrate. Other types of glues may be used if you so desire.
Apply some weight(s) to hold the join between the balsa and substrate in close contact. For rubber glue allow at least 24 hours for the glue to set.
Once the glue is fully set, use a flat smooth lapping plate and a sheet of sandpaper (about 320 grit) to lap the top surface of your balsawood perfectly flat. This is best done using the cross-hatch pencil method.
With the top surface of your balsawood now perfectly flat, you need to remove any loose pieces of balsawood (dust). This can be done using compressed air or a vacuum cleaner suction with a brush nozzle.
Your balsa strop is now ready for pasting.
5. EXAMPLES
Composite
300mm (12”) x 75mm (3”). 2 x 8mm structural foam + 1 x 6mm glazed tile + 10mm balsawood